U.S. patent number 10,033,512 [Application Number 15/198,137] was granted by the patent office on 2018-07-24 for method and system for harq operation and scheduling in joint tdd and fdd carrier aggregation.
This patent grant is currently assigned to BlackBerry Limited. The grantee listed for this patent is BlackBerry Limited. Invention is credited to Zhijun Cai, David Nigel Freeman, Yiping Wang.
United States Patent |
10,033,512 |
Wang , et al. |
July 24, 2018 |
Method and system for HARQ operation and scheduling in joint TDD
and FDD carrier aggregation
Abstract
A method at a user equipment for hybrid automatic repeat request
(HARQ) operation, the user equipment operating on a primary carrier
having a first duplex mode and on at least one secondary carrier
having a second duplex mode, the method using HARQ timing of the
first duplex mode if the timing of the first duplex mode promotes
acknowledgement opportunities over using HARQ timing of the second
duplex mode; and using HARQ timing of the second duplex mode if the
timing of the second duplex mode promotes acknowledgement
opportunities over using HARQ timing of the first duplex mode.
Inventors: |
Wang; Yiping (Allen, TX),
Cai; Zhijun (Ashburn, VA), Freeman; David Nigel
(Basingstoke, GB) |
Applicant: |
Name |
City |
State |
Country |
Type |
BlackBerry Limited |
Waterloo |
N/A |
CA |
|
|
Assignee: |
BlackBerry Limited (Waterloo,
Ontario, CA)
|
Family
ID: |
51589267 |
Appl.
No.: |
15/198,137 |
Filed: |
June 30, 2016 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20160308659 A1 |
Oct 20, 2016 |
|
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
14033256 |
Sep 20, 2013 |
9386602 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
74/02 (20130101); H04L 1/1854 (20130101); H04L
5/0055 (20130101); H04L 1/1861 (20130101); H04L
5/14 (20130101); H04L 1/1864 (20130101) |
Current International
Class: |
H04J
3/00 (20060101); H04L 5/14 (20060101); H04W
74/02 (20090101); H04L 1/18 (20060101); H04L
5/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
2690815 |
|
Jan 2014 |
|
EP |
|
2012128558 |
|
Sep 2012 |
|
WO |
|
Other References
The International Search Report and Written Opinion dated Dec. 16,
2014; in PCT patent application No. PCT/EP2014/069230. cited by
applicant .
LG Electronics; "CA-based aspects for FDD-TDD joint operation",
3GPP Draft; R1-133372 LGE-CA-Based FDD TDD, 3rd Generation
partnership project (3GPP) Aug. 10, 2013;
URL:http//www.3gpp.org/ftp/tsg_ran/WG1_R1/TSGR1_74/Docs. cited by
applicant .
3GPP TS 36.211, "Evolved Universal Terrestrial Radio Access
(E-UTRA); Physical Channels and Modulation," V.11.0.0 (Release 11),
Sep. 2012. cited by applicant .
3GPP TS 36.213, "Evolved Universal Terrestrial Radio Access
(E-UTRA); Physical layer procedures," V.11.2.0 (Release 11), Apr.
2013. cited by applicant .
3GPP TSG RAN meeting #60 RP-130888 Oranjestad, Aruba, Jun. 11-14,
2013 "New WI: L TE TDD-FDD Joint Operation" Nokia Corporation.
cited by applicant .
3GPP TS 36.321, "Evolved Universal Terrestrial Radio Access
(E-UTRA); Medium Access Control (MAC) protocol specification,"
V.11.1.0 (Release 11), Feb. 2013. cited by applicant .
3GPP TS 36.331, "Evolved Universal Terrestrial Radio Access
(E-UTRA); Radio Resource Control (RRC); Protocol specification,"
V.11.1.0 (Release 11), Nov. 2012. cited by applicant .
Office Action issued in Canadian Application No. 2,924,721 dated
Nov. 28, 2016; 4 pages. cited by applicant.
|
Primary Examiner: Yuen; Kan
Attorney, Agent or Firm: Fish & Richardson P.C.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation and claims priority to U.S.
Non-Provisional application Ser. No. 14/033,256, filed Sep. 20,
2013, the entire contents of which is hereby expressly incorporated
by reference herein in its entirety.
Claims
The invention claimed is:
1. A method, at a user equipment for subframe scheduling operation,
the user equipment operating on a primary carrier having a time
division duplex (TDD) mode and at least one secondary carrier
having a frequency division duplex (FDD) mode, the method
comprising: receiving on the primary carrier a Downlink Control
Information (DCI) on a Physical Downlink Control Channel (PDCCH),
the DCI comprising an assignment bitmap for the secondary carrier,
wherein each bit in the assignment bitmap corresponds to a
subframe, and wherein a value of each bit indicates whether the
corresponding subframe is scheduled; determining a plurality of
subframes from the assignment bitmap; scheduling on the secondary
carrier the subframes determined from the assignment bitmap;
wherein the assignment bitmap comprises a number of bits equal to a
number of consecutive uplink subframes of a TDD configuration of
the primary carrier following a current subframe plus one.
2. The method of claim 1, wherein only a subset of bits of the
assignment bitmap are used, the subset being selected based on a
TDD configuration of the primary carrier and a current
subframe.
3. The method of claim 2, wherein the subset comprises a number of
bits equal to a number of consecutive uplink subframes of the TDD
configuration following the current subframe plus one.
4. The method of claim 3, wherein bits of the assignment bitmap
which are not in the subset include scheduling information for a
next available downlink subframe.
5. The method of claim 1, wherein the assignment bitmap comprises a
first field indicating a number of subframes and a second field
indicating a subframe offset, and wherein the scheduling comprises
scheduling the number of consecutive subframes starting from the
indicated subframe offset.
6. The method of claim 1, further comprising a plurality of
resource allocations, each resource allocation comprising an offset
field indicating a subframe based on a current subframe.
7. The method of claim 1, wherein the scheduled subframes are
uplink subframes.
8. The method of claim 7, wherein a Hybrid Automatic Repeat reQuest
(HARD) process identifier for each scheduled subframe is determined
from a subframe number.
9. The method of claim 1, wherein the assignment bitmap comprises
an index which maps to a subframe position relative to a current
subframe.
10. A user equipment operating on a primary carrier having a time
division duplex (TDD) mode and at least one secondary carrier
having a frequency division duplex (FDD) mode, the user equipment
comprising: a processor; and a communications subsystem; wherein
the processor and communication subsystem cooperate to: receive on
the primary carrier a Downlink Control Information (DCI) on a
Physical Downlink Control Channel (PDCCH), the DCI comprising an
assignment bitmap for the secondary carrier, wherein each bit in
the assignment bitmap corresponds to a subframe, and wherein a
value of each bit indicates whether the corresponding subframe is
scheduled; determine a plurality of subframes from the assignment
bitmap; schedule on the secondary carrier the subframes determined
from the assignment bitmap; wherein the assignment bitmap comprises
a number of bits equal to a number of consecutive uplink subframes
of a TDD configuration of the primary carrier following a current
subframe plus one.
11. The user equipment of claim 10, wherein only a subset of bits
of the assignment bitmap are used, the subset comprising a number
of bits equal to a number of consecutive uplink subframes of the
TDD configuration following the current subframe plus one.
12. The user equipment of claim 11, wherein bits of the assignment
bitmap which are not in the subset include scheduling information
for a next available downlink subframe.
13. The user equipment of claim 10, wherein the assignment bitmap
comprises a first field indicating a number of subframes and a
second field indicating a subframe offset, and wherein the
scheduling comprises scheduling the number of consecutive subframes
starting from the indicated subframe offset.
14. The user equipment of claim 10, wherein the assignment bitmap
comprises a plurality of resource allocations, each resource
allocation comprising an offset field indicating a subframe based
on a current subframe.
15. The user equipment of claim 10, wherein the scheduled subframes
are uplink subframes.
16. The user equipment of claim 10, wherein a Hybrid Automatic
Repeat reQuest (HARQ) process identifier for each scheduled
subframe is determined from a subframe number.
Description
FIELD OF THE DISCLOSURE
The present disclosure relates to hybrid automatic repeat request
(HARQ) operation and scheduling in carrier aggregation, and in
particular relates to HARQ operation and scheduling in carrier
aggregation systems using combined frequency division duplex (FDD)
and time division duplex (TDD) modes.
BACKGROUND
In the 3.sup.rd Generation Partnership Project (3GPP) Long Term
Evolution (LTE) Architecture, downlink and uplink transmissions are
organized into one of two duplex modes. These modes are frequency
division duplex mode and a time division duplex mode. Frequency
division duplex mode uses paired spectrum to separate the uplink
and downlink transmissions while the TDD mode uses a common
spectrum and relies on time multiplexing to separate uplink and
downlink transmissions.
With FDD, the acknowledgement for a transmission typically occurs a
set number of subframes after the transmission has been received.
For example, in many systems the acknowledgement is sent back to
the network from the user equipment (UE) four subframes after
receipt of the transmission. In TDD, depending on the TDD mode, the
HARQ feedback is sent in a predefined manner to the network once a
transmission is received.
In order to increase data throughput, carrier aggregation may be
utilized in LTE-advanced systems. To support 3GPP carrier
aggregation, a LTE-advanced UE may simultaneously receive or
transmit on one of multiple component carriers. In some cases,
component carriers utilize the same duplex mode, and the HARQ
operation and scheduling of the component carriers is therefore
relatively straightforward. However, in some cases a secondary
component carrier may be operating in a different duplex mode than
a primary component carrier. In this case, the HARQ operation and
scheduling are currently undefined.
BRIEF DESCRIPTION OF THE DRAWINGS
The present disclosure will be better understood with reference to
the drawings, in which:
FIG. 1 a graph showing an example of uplink and downlink subframes
in a frequency division duplex mode;
FIG. 2 is a graph showing an example of uplink and downlink
subframes in a time division duplex mode;
FIG. 3 is a timing diagram showing HARQ operation on a secondary
FDD carrier with a primary carrier in TDD mode utilizing FDD PDSCH
HARQ timing;
FIG. 4 is a timing diagram showing PDSCH HARQ and scheduling timing
of a secondary FDD carrier from a primary carrier in TDD mode;
FIG. 5 is a timing diagram showing PUSCH HARQ and scheduling timing
of a secondary FDD carrier from a primary carrier in TDD mode;
FIG. 6 is a timing diagram showing a secondary FDD carrier
utilizing the TDD configuration PDSCH HARQ timing of the primary
cell;
FIG. 7 is a timing diagram showing HARQ operation on a secondary
FDD carrier with a primary TDD carrier utilizing FDD PDSCH HARQ
timing;
FIG. 8 is a flow diagram showing selection of HARQ timing operation
on a secondary carrier;
FIG. 9 is a timing diagram showing a secondary FDD carrier
utilizing TDD configuration 2 timing for HARQ operation for a
primary carrier having 5 ms periodicity;
FIG. 10 is a timing diagram showing a secondary FDD carrier
utilizing TDD configuration 5 timing for HARQ operation for a
primary carrier having 10 ms periodicity;
FIG. 11 is a flow diagram showing a selection of a TDD
configuration for HARQ operation on a secondary carrier;
FIG. 12 is a timing diagram showing a secondary FDD carrier
utilizing TDD configuration 5 timing for HARQ operation;
FIG. 13 is a timing diagram showing HARQ operation on a secondary
FDD carrier utilizing a next available subframe on a primary TDD
carrier;
FIG. 14 is a timing diagram showing cross carrier scheduling from a
primary TDD carrier for a secondary FDD carrier;
FIG. 15 is a block diagram showing a bitmap for use with cross
carrier scheduling;
FIG. 16 is a timing diagram showing a timing scheme of PUSCH HARQ
of a secondary FDD carrier for cross carrier scheduling from a TDD
carrier;
FIG. 17 is a simplified block diagram of an example network
element; and
FIG. 18 is a block diagram of an example user equipment.
DETAILED DESCRIPTION OF THE DRAWINGS
The present disclosure provides a method at a user equipment for
hybrid automatic repeat request (HARQ) operation, the user
equipment operating on a primary carrier having a first duplex mode
and on at least one secondary carrier having a second duplex mode,
the method comprising: using HARQ timing of the first duplex mode
if the timing of the first duplex mode promotes acknowledgement
opportunities over using HARQ timing of the second duplex mode; and
using HARQ timing of the second duplex mode if the timing of the
second duplex mode promotes acknowledgement opportunities over
using HARQ timing of the first duplex mode.
The present disclosure further provides a user equipment for hybrid
automatic repeat request (HARQ) operation, the user equipment
operating on a primary carrier having a first duplex mode and on at
least one secondary carrier having a second duplex mode, the user
equipment comprising a processor configured to: use HARQ timing of
the first duplex mode if the timing of the first duplex mode
promotes acknowledgement opportunities over using HARQ timing of
the second duplex mode; and use HARQ timing of the second duplex
mode if the timing of the second duplex mode promotes
acknowledgement opportunities over using HARQ timing of the first
duplex mode.
In an LTE system, downlink and uplink transmissions are organized
into one of two duplex modes, namely FDD and TDD modes. FDD mode
uses paired spectrum to separate the uplink and downlink
transmissions, while in TDD mode, common spectrum is used and the
mode relies on time multiplexing to separate uplink and downlink
transmissions.
While the present disclosure is described below with regard to
3.sup.rd Generation Partnership Project (3GPP) Long Term Evolution
Network Architecture, the present disclosure is not limited to LTE.
Other network architectures including a TDD mode and an FDD mode
may also utilize the HARQ operation and scheduling embodiments
described herein.
Reference is now made to FIG. 1, which shows downlink and uplink
transmissions for an FDD mode. In particular, the embodiment of
FIG. 1 has a first channel 110 and a second channel 112. Channel
110 is used for uplink subframes 120, while channel 112 is used for
downlink subframes 122.
Referring to FIG. 2, a time division duplex system is shown having
only one channel 210, where the downlink and uplink subframes are
duplexed together on the channel. In particular, in the embodiment
of FIG. 2, downlink subframes 220 and 222 are interspersed with
uplink subframes 230 and 232.
While the embodiment of FIG. 2 shows an alternation between uplink
and downlink subframes, other configurations are possible.
Specifically, in a 3GPP LTE TDD system, a subframe of a radio frame
can be a downlink, an uplink, or a special subframe. The special
subframe comprises downlink and uplink time regions separated by a
guard period to facilitate downlink to uplink switching. In
particular, each special subframe includes three parts: a downlink
pilot time slot (DwPTS), an uplink pilot time slot (UpPTS) and a
guard period (GP). Physical downlink shared channel (PDSCH)
transmissions may be made in a downlink subframe or in the DwPTS
portion of a special subframe.
The 3GPP Technical Specification (TS) 36.211, "Evolved Universal
Terrestrial Radio Access (E-UTRA); Physical Channels and
Modulation", v.11.0.0, Sep. 19, 2012, the contents of which are
incorporated herein by reference, defines seven different
uplink/downlink configuration schemes in LTE TDD operations. These
are shown below with regard to Table 1.
TABLE-US-00001 TABLE 1 LTE TDD Uplink-Downlink Configurations
Downlink-to- Uplink- Uplink downlink Switch-point Subframe number
configuration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U D S
U U U 1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms
D S U U U D D D D D 4 10 ms D S U U D D D D D D 5 10 ms D S U D D D
D D D D 6 5 ms D S U U U D S U U D
In Table 1 above, the "D" is for a downlink subframe, the "U" is
for uplink subframes, and the "S" is for special subframes.
Thus, as shown in Table 1 above, there are two switching point
periodicities specified in the LTE standard for TDD. They are 5 ms
and 10 ms, of which the 5 ms switching point periodicity is
introduced to support the co-existence between LTE and low chip
rate universal terrestrial radio access (UTRA) TDD systems. The 10
ms switching point periodicity is for the coexistence between LTE
and a high chip rate UTRA TDD system.
The seven UL/DL configurations of Table 1 cover a wide range of
uplink/downlink allocations, ranging from downlink heavy 1:9 ratio
in configuration 5 to UL heavy 3:2 ratio in configuration 0.
Based on the configurations, as compared to FDD systems, TDD
systems have more flexibility in terms of the proportion of
resources assignable to uplink and downlink communications within a
given assignment of spectrum. In other words, TDD systems can
distribute the radio resources unevenly between the uplink and the
downlink, enabling potentially more efficient radio resource
utilization by selecting an appropriate uplink/downlink
configuration based on interference situations and different
traffic characteristics in the uplink and downlink.
HARQ provides an acknowledgement or a negative acknowledgement of
the reception of a data transmission. In an LTE FDD system, the UE
and evolved node B (eNB) processing times for both the downlink and
uplink receipt are fixed because of the continuous downlink and
uplink transmission and reception and invariant downlink and uplink
subframe configuration. In particular, the UE, upon detection on a
given serving cell of a physical downlink control channel (PDCCH)
with a downlink control information (DCI) format 0/4 and/or a
physical HARQ indication channel (PHICH) transmission in subframe n
intended for the UE, adjusts the corresponding physical uplink
shared channel (PUSCH) transmission in subframe n+4 according to
the PDCCH and PHICH information.
On the downlink, the UE, upon detection of the PDSCH transmission
in subframe n-4 intended for the UE and for which an
HARQ-acknowledgement is provided, transmits the HARQ
acknowledgement response in subframe n.
Conversely, in a TDD system, since the uplink and downlink
transmissions are not continuous, such that the transmissions do
not occur in every subframe, the scheduling and HARQ timing
relationships are separately defined in the LTE specifications.
Currently, the HARQ ACK/NACK timing relationship for the downlink
is defined by Table 10.1.3.1-1 in the 3GPP TS 36.213, "3rd
Generation Partnership Project; Technical Specification Group Radio
Access Network; Evolved Universal Terrestrial Radio Access
(E-UTRA); Physical layer procedures (Release 11)", v. 11.3.0, June
2013, the contents of which are incorporated herein by reference.
The table is reproduced in Table 2 below.
In Table 2, an association is made between an uplink subframe n,
which conveys the ACK/NACK, with downlink subframes n-k.sub.i, i=0
to M-1. For example, with uplink/downlink TDD configuration 0,
subframe 2 will convey an ACK/NACK bit for the PDSCH on subframe
6.
TABLE-US-00002 TABLE 2 Downlink Association Set Index K: {k.sub.0,
k.sub.1, . . . k.sub.M-1} UL-DL Subframe n configuration 0 1 2 3 4
5 6 7 8 9 0 -- -- 6 -- 4 -- -- 6 -- 4 1 -- -- 7, 6 4 -- -- -- 7, 6
4 -- 2 -- -- 8, 7, 4, 6 -- -- -- -- 8, 7, -- -- 4, 6 3 -- -- 7, 6,
11 6, 5 5, 4 -- -- -- -- -- 4 -- -- 12, 8, 7, 11 6, 5, -- -- -- --
-- -- 4, 7 5 -- -- 13, 12, 9, 8, -- -- -- -- -- -- -- 7, 5, 4, 11,
6 6 -- -- 7 7 5 -- -- 7 7 --
Further, in 3GPP TS 36.213, Table 8.3-1, which is shown below with
regard to Table 3, indicates that the PHICH ACK/NACK received in a
downlink sub-frame i is linked with the uplink data transmission in
the uplink subframe i-k, where k is given in Table 3. For example,
with the uplink/downlink TDD configuration 1, subframe 1 conveys
the ACK/NACK bit for the PUSCH on subframe 7 (i=1, k=4 from Table 3
below, thus i-k=subframe 7). Additionally, for the uplink/downlink
configuration 0, in subframes 0 and 5, when the I.sub.PHICH=1, k=6.
This is because there may be two ACK/NACKs for a UE transmitted on
the PHICH in subframes 0 and 5, one being represented by
I.sub.PHICH=1 and the other by I.sub.PHICH=0.
TABLE-US-00003 TABLE 3 k for HARQ ACK/NACK TDD UL-DL Subframe
number i configuration 0 1 2 3 4 5 6 7 8 9 0 7 4 7 4 1 4 6 4 6 2 6
6 3 6 6 6 4 6 6 5 6 6 6 4 7 4 6
The uplink grant, ACK/NACK and transmission/retransmission
relationship provided below with regard to Table 4. Table 4
represents Table 8.2 of the 3GPP TS 36.213 Technical
Specification.
TABLE-US-00004 TABLE 4 k for PUSCH transmission TDD UL-DL Subframe
number n configuration 0 1 2 3 4 5 6 7 8 9 0 4 6 4 6 1 6 4 6 4 2 4
4 3 4 4 4 4 4 4 5 4 6 7 7 7 7 5
In Table 4, the UE, upon detection of a PDCCH with DCI format 0/4
and/or a PHICH transmission in subframe n intended for the UE,
adjusts the corresponding PUSCH transmission in sub-frame n+k,
where k is given in the table.
For example, for TDD uplink/downlink configuration 0, if the least
significant bit (LSB) of the uplink index in the DCI format 0/4 is
set to 1 in sub-frame n or a PHICH is received in sub-frame n=0 or
5 in the resource corresponding to I.sub.PHICH=1, or the PHICH is
received in sub-frame n=1 or 6, the UE may adjust the corresponding
PUSCH transmission in sub-frame n+7.
If, for TDD uplink/downlink configuration 0, both the most
significant bit and least significant bit of the UL index in the
DCI format 0/4 are set in sub-frame n, the UE may adjust the
corresponding PUSCH transmission in both sub-frames n+k and n+7,
where k is given by Table 4.
As seen above, both grant and HARQ timing linkage in TDD are more
complicated than the fixed time linkages used in LTE FDD
systems.
Carrier Aggregation
To meet the need of rapidly growing UE throughput, a maximum of 100
MHz bandwidth is specified for the LTE-advanced systems. Carrier
aggregation enables multiple component carriers, which use up to 20
MHz bandwidth, to be aggregated to form a wider total
bandwidth.
To support 3GPP carrier aggregation, in LTE-A, a UE may
simultaneously receive or transmit on one or multiple component
carriers (CCs). Multiple CCs could be from the same eNB or from
different eNBs. In an FDD system, the number of CCs aggregated in
the downlink could be different from that in the uplink.
For CA, there is one independent hybrid-ARQ entity per serving cell
in each of the uplink or downlink. Multiple aggregated cells
(carriers) use multiple HARQ entities. However, each UE has only
one radio resource control (RRC) connection with the network.
The serving cell handling the RRC connection establishment or
re-establishment or handover is referred to as the Primary Cell
(PCell). The carrier corresponding to the PCell in the downlink is
termed the downlink primary component carrier (DL PCC) while in the
uplink the uplink primary component carrier (UL PCC).
Other serving cells are referred to as secondary cells (SCells) and
their corresponding carriers are referred to as secondary component
carriers (SCC).
The carriers may be aggregated intra-band, such that they use the
same operational band, and/or inter-band, where a different
operational band is used.
The configured serving cell set for a UE consists of one PCell and
one or more SCells.
Cross Carrier Scheduling
In addition to the normal carrier self-scheduling in Release 8 or 9
of the LTE specifications, cross-carrier scheduling is also
possible. A PDCCH on one carrier can relate to data on the PDSCH or
PUSCH of another carrier. Self-scheduling means that the shared
data channel, PDSCH or PUSCH, of a carrier is scheduled by the
PDCCH which is transmitted on the same carrier, while
cross-scheduling means that the shared data channel, PDSCH or
PUSCH, of a carrier is scheduled by the PDCCH which is transmitted
on another carrier.
For carrier aggregation, information on the component carriers that
a UE needs to monitor is notified by the eNB via MAC and RRC
messaging. This may help reduce the UE's power consumption as the
UE only needs to monitor the component carriers configured for
possible scheduling information.
For a UE monitoring more than one component carrier, the scheduling
information for each subframe is sent on a scheduling carrier. In
particular, the scheduling carrier could be a PCell or SCell.
However, the PCell can only be scheduled by the PCell itself.
Further, the PUCCH is only allowed to be transmitted on the PCell.
This is the same for FDD and TDD systems.
For uplink grants, after demodulation of PUSCH, the corresponding
uplink ACK or NACK is carried by the PHICH, which is transmitted
from the scheduling carrier. This is the same for FDD and TDD
systems.
In 3GPP TS36.331, "3rd Generation Partnership Project; Technical
Specification Group Radio Access Network; Evolved Universal
Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC);
Protocol specification (Release 11)", v. 11.4.0, June 2013, the
contents of which are incorporated herein by reference, networks
can send an RRC configuration message containing a
CrossCarrierSchedulingConfig information element (IE) to further
configure the cross-carrier scheduling. The
CrossCarrierSchedulingConfig IE includes at least the following
fields: a. schedulingCellID: to notify a UE where (at which
cell/carrier) to monitor the PDCCH (self-scheduling or
cross-carrier scheduling). b. pdsch-Start: the starting OFDM symbol
of PDSCH for the concerned SCell. Values 1, 2, 3 are applicable
when dl-Bandwidth for the concerned SCell is greater than 10
resource blocks, values 2, 3, 4 are applicable when dl-Bandwidth
for the concerned SCell is less than or equal to 10 resource
blocks. This can be treated as a virtual PCFICH.
The activation/deactivation of component carriers is done via MAC
control elements. As a result, a UE with cross-carrier scheduling
and with more than one carrier activated needs only to monitor the
PDCCH on the scheduling cell. In other words, there is no need to
monitor the PDCCH on the scheduled cell and there is no need to
detect the physical control format indicator channel (PCFICH) to
derive the starting symbol of the PDSCH for the scheduled cell.
Regarding the above, although the current LTE specifications can
operate in two different duplex modes, it is unclear how a device
would operate jointly between an FDD and a TDD duplex mode.
Specifically, the use of combined FDD/TDD joint operation enables
effective use of reallocated spectrum through a combination of two
duplex modes. For example, a first deployment scenario of TDD/FDD
joint operation may be by carrier aggregation. This supports either
TDD or FDD as the primary cell. Given the fact that the current
HARQ operation is defined separately for TDD and FDD modes, and
since they are largely different, the use of HARQ operations will
run into some issues when two modes are jointly operated.
With regard to HARQ timing and scheduling issues, the various
embodiments below are described with regard to the TDD carrier
being configured as the primary cell and an FDD carrier being a
secondary cell. However, this is not limiting and the embodiments
described herein could equally be used with the FDD being the
primary carrier.
Reference is now made to FIG. 3. As indicated above, only one PUCCH
exists and is configured at the primary carrier. Thus HARQ for
secondary carriers proceeds through the primary carrier.
FIG. 3 shows a self-scheduling case of PDSCH HARQ timing where a
TDD primary carrier 310 with configuration 1 is aggregated with an
FDD secondary carrier 320.
As seen in FIG. 3, the FDD uses self-scheduling ACKs, which are
provided in four subframes from the received downlink transmission.
Thus, the FDD carrier follows the existing FDD timing rules of the
PDSCH HARQ-ACK. In the embodiment of FIG. 3, the PDSCH transmitted
on subframes 0, 1, 2, 5, 6 and 7 cannot be properly acknowledged as
shown by arrows 330 if using the PUCCH, due to the lack of an
uplink subframe on the TDD primary carrier.
Further, referring to FIG. 4, for the same carrier aggregation case
with cross-carrier scheduling, where the PDCCH on one carrier
relates to data on another carrier, the PDSCH scheduling and HARQ
timing is illustrated for such cross-carrier scheduling.
In particular, the primary carrier 410 operates in a TDD mode
(configuration 1), whereas the secondary carrier 420 operates in an
FDD mode. The scheduling is shown for example with references 430,
432, 434, 436.
As seen in FIG. 4, since subframes 2 and 3 on the primary carrier
410 are uplink subframes, subframes 2 and 3 on the FDD secondary
carrier 420 cannot be scheduled.
In the embodiment of FIG. 4, the TDD is in configuration 1 and
therefore subframes 2, 3, 7 and 8 cannot be cross-carrier
scheduled.
The HARQ timing, shown for example with line 440 for HARQ on the
secondary carrier 420 in subframe 9, may work properly for the
subframes that are scheduled utilizing the TDD configuration for
HARQ.
Similarly for the uplink, with FDD PUSCH and cross-carrier
scheduling from a TDD carrier, the TDD PUSCH scheduling timing can
only be used for subframes 1, 4, 6 and 9, as shown in FIG. 5.
In FIG. 5, the TDD configured carrier is the primary carrier 510
and the FDD configured carrier is the secondary carrier 520. As
seen in FIG. 5, only subframes 1, 4, 6 and 9 may be used to
schedule (6, 4, 6, 4 subframes later as in Table 4 above),
therefore allowing only uplink subframes 2, 3, 7 and 8 to be
cross-carrier scheduled from the TDD carrier. All other uplink
subframes on the FDD carrier would become unusable for the UE.
In accordance with the above, various embodiments are provided
below to overcome the HARQ operations and scheduling issues.
PDSCH HARQ-ACK Embodiments
Flexible PDSCH HARQ-ACK Timing
In accordance with one embodiment of the present disclosure,
existing PDSCH HARQ-ACK timing may be fully reused for both TDD and
FDD modes. No new PDSCH HARQ-ACK timing is required and the
embodiment is applicable to both self and cross-carrier
scheduling.
In particular, when a PCell is TDD and SCell is FDD, for the TDD
carrier, the PDSCH HARQ-ACK timing follows timing corresponding to
its own uplink/downlink TDD configuration. The PDSCH HARQ timing of
the FDD carrier follows the reference timing. The reference timing
is determined based on the primary cell TDD uplink/downlink
configuration.
In particular, reference is now made to FIG. 6 in which primary
cell 610 has a TDD configuration and secondary cell 620 has an FDD
configuration. As seen in the embodiment of FIG. 6, the frames on
the FDD carrier 620 that correspond with downlink or special
subframes of TDD carrier 610 utilize the same HARQ timing. In other
words, the subframes on FDD carrier 620 utilize the TDD
configuration 1 timing for the subframes corresponding to downlink
or special subframes.
Thus, as shown by arrows 630, the ACKs/NACKs are provided in the
subframe corresponding to the configuration 1 timing. Thus, for
subframe 0, the acknowledgement is provided in subframe 7 on the
uplink for the TDD configuration 1. Similarly, subframe 1 is
acknowledged on subframe 7 and subframe 4 is acknowledged on
subframe 8.
In accordance with this embodiment, subframes 2, 3, 7 and 8 will
not be able to be acknowledged.
The above may be therefore more useful when the PCell configuration
is downlink subframe heavy. As will be appreciated by those in the
art, when the TDD configuration is uplink heavy, a significant
number of downlink subframes on the FDD carrier will be
unusable.
Thus, with the embodiment of FIG. 6, the majority of the downlink
PDSCHs are able to be properly acknowledged or negatively
acknowledged, leaving a small portion of PDSCHs which do not have
ACK/NACK linkage. In this case, the eNB may simply pass the ACK to
a higher layer and let the RRC handle the package error.
When comparing the embodiment of FIG. 6 with that of only following
FDD timing, the above is able to acknowledge 60% of the of the
PDSCH downlink subframes, while only 40% of the PDSCH subframes can
be acknowledged or negatively acknowledged when following FDD
timing.
On the other hand, when the primary cell TDD configuration is
uplink subframe heavy, the reference timing may, in one embodiment,
utilize the FDD PDSCH HARQ timing. Reference is now made to FIG. 7,
which shows an example of FDD PDSCH HARQ timing using the TDD
configuration 0 as primary cell. In accordance with Table 1 above,
the configuration 0 is uplink subframe heavy with a ratio of
3:2.
In particular, the primary cell 710 is a TDD configuration 0 and
the secondary cell 720 is an FDD configuration. As seen by arrows
730, the configuration allows subframes 3, 4, 5 and 8, 9, 0 to be
acknowledged four subframes later.
In the example of FIG. 7, 60% of the PDSCHs are able to be properly
acknowledged by following the FDD timing and 40% of the PDSCHs are
not able to have an acknowledgement linkage.
Thus, in accordance with FIGS. 6 and 7, a decision can be made
based on the configuration of the TDD at the primary cell as to
which embodiment to use. The decision may be based on the
efficiency of the HARQ technique, and the selection of whichever is
more efficient is made. In the case where it is equally efficient
to use either technique, (e.g. if the number of uplink subframes is
the same as the number of downlink subframes in the TDD
configuration of the primary cell), either the TDD configuration of
the primary cell or the FDD HARQ timing can be considered as the
reference timing.
Reference is now made to FIG. 8, which shows a process diagram of
the above. In particular, the process of FIG. 8 starts at block 810
and proceeds to block 820 in which a precondition is that a TDD
primary cell is aggregated with FDD secondary cells.
The process then proceeds to block 830 in which a check is made to
determine whether it is more efficient to use TDD timing or FDD
timing. For example, the determination for each of the secondary
cells may be whether the number of uplink subframes is greater than
the number of downlink subframes in the primary cell TDD
configuration.
From block 830, if the TDD configuration is less efficient, the
process proceeds to block 832 in which the FDD PDSCH timing is
used, as shown in FIG. 7 above.
Conversely, if the TDD configuration is more efficient, for example
if the number of DL subframes exceeds the number of UL subframes,
the process proceeds from block 830 to block 840 in which the
primary cell TDD PDSCH timing is utilized for the acknowledgements,
as shown above with regards to FIG. 6.
If it is equally efficient to use either timing, for example if the
number of uplink subframes and the number of downlink subframes are
equal, then either the PCell TDD or the FDD PDSCH timing may be
utilized. The choice may be specified for example in various
standards or made by the carrier to a UE. In this case the process
proceeds to block 850.
From blocks 832, 840 or 850, the process proceeds to block 860 and
ends.
In one embodiment, the selection of the PDSCH HARQ timing may be
handled by higher layer signalling. For example, the selection of
the PDSCH HARQ timing may be embedded in the RRC reconfiguration
message when the FDD SCell is added to the primary TDD carrier. In
another example, the selection of the PDSCH HARQ timing may be
embedded in a MAC control elements signalled to the UE.
Switching Periodicity Based Embodiment
In a further embodiment, the FDD secondary cell may be provided
with a TDD uplink/downlink configuration utilizing a specific TDD
configuration, regardless of the actual TDD configuration of the
primary cell. In particular, the reference timing can follow TDD
uplink/downlink configuration 2 from Table 1 above if the primary
cell TDD configuration switching periodicity is 5 ms and timing may
follow TDD uplink/downlink configuration 5 for switching
periodicity of 10 ms.
Reference is now made to FIG. 9, which shows an example of the
timing method with a TDD configuration 1 as the primary cell.
In particular, as seen in FIG. 9, the primary cell 910 has TDD
configuration 1 whereas the secondary cell 920 has an FDD
configuration.
From Table 1 above, utilizing configuration 2 with a 5 ms
periodicity, the uplink subframes are in subframes 2 and 7, which
are used to provide the HARQ feedback. Thus, referring to FIG. 9,
as shown by arrows 930, subframes 4, 5, 6 and 8 utilize subframe 2
in the next frame for the HARQ feedback. Similarly, subframes 9, 0,
1 and 3 utilize subframe 7 for the HARQ feedback.
FIG. 9 therefore shows an example where 80% of the PDSCH subframes
can be properly acknowledged.
When the TDD switching periodicity is 10 ms, TDD configuration 5
PDSCH HARQ timing is used. From Table 1, configuration 5 only has
one uplink subframe and thus the ability of the ACK/NACK is
increased to 90%.
In particular, reference is made to FIG. 10 which shows an example
of the timing method with a TDD configuration 3 as the primary cell
1010. The secondary cell 1020 has an FDD configuration. As TDD
configuration 3 has a 10 ms periodicity, the TDD configuration 5
PDSCH HARQ timing is used.
Thus, as seen in FIG. 10, every subframe (except subframe 2) uses
subframe 2 of the primary cell for acknowledgement. The
acknowledgement, as with all embodiments herein, must be delayed by
a minimum processing time, for example 4 subframes, and thus for
subframes 9, 0 and 1 the acknowledgement waits until subframe 2 in
a subsequent frame for the acknowledgement. The acknowledgements
are shown with arrows 1030 in the example of FIG. 10.
A process at a user equipment to determine which of the embodiments
of FIGS. 9 and 10 above to use is provided with regard to FIG. 11.
In particular, the process of FIG. 11 starts at block 1110 and
proceeds to block 1120 in which a precondition is at a TDD primary
cell is aggregated with FDD secondary cells.
The process then proceeds to block 1130 in which a determination is
made whether the switching periodicity is 5 ms or 10 ms. From block
1130, if the periodicity is 5 ms the process proceeds to block 1135
in which TDD configuration 2 is used on the secondary cell for the
PDSCH ACK timing.
Conversely, from block 1130 if the periodicity is 10 ms then the
process proceeds to block 1140 in which the TDD configuration 5
PDSCH timing is utilized.
From blocks 1135 and 1140 the process proceeds to block 1150 and
ends.
In a further alternative embodiment, the timing for TDD
configuration 5 PDSCH HARQ may be used regardless of the TDD
switching periodicity.
Reference is now made to FIG. 12, which illustrates one example of
the alternative embodiment. In particular, the primary cell has a
TDD configuration 1, as shown by reference numeral 1210 and the
secondary cell 1220 has an FDD downlink configuration.
The example of FIG. 12 shows, using arrows 1230, that every
subframe besides subframe 2 is able to provide ACK/NACK feedback on
the subframe 2 of the primary cell.
From FIG. 12, the specific TDD configuration for the primary cell
is irrelevant as all current TDD configurations have an uplink
subframe at subframe 2.
ACK/NACK on Next Available Uplink Subframe
In a further embodiment, an ACK or NACK may be provided on all
downlink PDSCH transmissions on every possible downlink subframe of
the secondary carrier. This embodiment provides a way of
transmitting the ACK/NACK bits on the next available TDD uplink
subframe for the FDD PDSCH subframe that does not have a linked
uplink subframe for an ACK/NACK transmission according to existing
FDD PDSCH HARQ-ACK timing. In another embodiment, the next
available rule may be specified in the standards, e.g. in a tabular
form.
However, the processing delay still needs to be taken into
consideration and thus the next available uplink subframe must be
at least four subframes after the current one in one
embodiment.
Reference is now made to FIG. 13, which shows an example of the
embodiment. In the embodiment of FIG. 13, primary cell 1310 has a
TDD configuration 1 whereas the secondary cell 1320 has an FDD
configuration. In FIG. 13, as shown by arrows 1330, uplink subframe
7 provides acknowledgements for subframes 0, 1, 2 and 3.
Further, in the embodiment of FIG. 13, uplink subframe 8 is used to
acknowledge subframe 4 and subframe 2 is used to acknowledge
subframes 5, 6, 7, and 8. Subframe 3 is used to acknowledge
subframe 9.
An eNB may decode the ACK or NACK for a corresponding FDD PDSCH
based on the next availability rule above. In particular, the eNB
would know that subframes 0, 1, 2 and 3 would provide their
acknowledgement on subframe 7 as the eNB knows the TDD
configuration of the UE. Similarly, the eNB would know where the
remaining subframes provide their acknowledgments.
Balanced Load of ACK/NACK Bits
In a further alternative embodiment to the ACK/NACK on the next
available uplink subframe, the distributing the ACK/NACK bits among
available TDD uplink subframes to achieve a more balanced and
optimal use of physical uplink controlled channel resources is
provided. Such acknowledgements may be implemented utilizing a
look-up table, for example.
In the present embodiment, the ACK/NACK bits may be spread to
distribute them more evenly while keeping the change to the
existing scheme as small as possible.
Currently, TDD HARQ ACK/NACK timing relationships for downlinks are
defined by Section 10.1.3.1-1 of the 3GPP TS 36.213 Specification
provided above. Table 2 above may be modified to accommodate the
provision of ACK/NACK bits for PDSCH transmitted on a FDD carrier
and is shown below with regard to Table 5.
TABLE-US-00005 TABLE 5 Downlink Association Set Index K: {k.sub.0,
k.sub.1, . . . k.sub.M-1} UL- DL Subframe n config. 0 1 2 3 4 5 6 7
8 9 0 -- -- 6 5, 6 4, 5 -- -- 6 5, 6 4, 5 1 -- -- 7, 6 4, 5, 6 --
-- -- 7, 6 4, 5, 6 2 -- -- 8, 7, 4, -- -- -- -- 8, 7, 4, -- -- 6, 5
6, 5 3 -- -- 11, 10, 6, 7, 5, 4, -- -- -- -- -- 9, 8 8 6 4 -- --
12, 8, 6, 5, -- -- -- -- -- -- 11, 10, 4, 7, 9 8 5 -- -- 13, 12, --
-- -- -- -- -- -- 9, 8, 7, 5, 4, 11, 6, 10 6 -- -- 7, 8 7, 6 5, 6
-- -- 5, 6 5, 6 --
Table 5 is only one example of an embodiment of timing for a
balanced load of ACK/NACK bits and other options exist. In
accordance with the example of Table 5, the TDD uplink subframe n
is associated with an FDD downlink subframe n-k.sub.i, i=0 to M-1.
The TDD uplink subframe n is used to convey ACK/NACK bits.
The embodiment of Table 5 ensures that each subframe in an FDD
frame can always be associated with an uplink subframe of the TDD
carrier with all existing TDD uplink/downlink configurations and
that the processing delay allowance of four subframes is
maintained.
Scheduling Embodiments
Due to the lack of PDCCH subframes in the TDD radio frame, some
PDSCH and PUSCH frames may not be able to be scheduled by
cross-carrier scheduling from the TDD carrier using current
techniques. Thus, in the embodiments below, the ability to schedule
every uplink and downlink subframe on an FDD carrier when a TDD
carrier is configured to cross carrier schedule the FDD carrier are
provided.
In a first embodiment, multi-subframe scheduling is provided.
Multi-subframe scheduling is used to schedule multiple subframes
via a single PDCCH. This is applicable to both downlink and uplink
subframes.
Reference is now made to FIG. 14, which provides a block diagram
showing a TDD PCell 1410 and an FDD secondary cell 1420. In the
embodiment of FIG. 14, the special cells are considered to be
downlink cells and can be used to schedule multiple FDD
subframes.
In particular, TDD PCell 1410 has TDD configuration 1 and thus
subframe 0 is a downlink subframe, subframe 1 is a special subframe
and subframes 2 and 3 are uplink subframes.
In accordance with the embodiment of FIG. 14, as shown by arrows
1430, subframes 2 and 3 of the FDD downlink are scheduled by
subframe 1 on the TDD carrier. Similarly, subframes 7 and 8 of the
FDD downlink may be scheduled by subframe 6 from the TDD carrier.
In this way, all downlink subframes in the FDD carrier can be
scheduled.
Multiple cross-carrier scheduling may be realized through the
interaction of a bitmap field in existing PDSCH assignment DCIs to
represent the number of PDSCH assignments and the position of these
assignments. For example, reference is now made to FIG. 15, which
shows a bitmap having four bits. In particular, bitmap 1510
includes bits 1512, 1514, 1516 and 1518.
From Table 1 above, the highest number of multiple PDSCH
cross-carrier scheduling required is 4 since the maximum number of
consecutive uplink subframes is 3 plus the current subframes. In
this case, a four bit bitmap field is used to deal with all
scenarios. In the bitmap a "1" may represent the PDSCH assignment
presence at the subframe location and a "0" may indicate an absence
of an assignment at that location.
In one embodiment bit 1512 may represent the current subframe and
the 3 bits next to the bit 1512 are used for subsequent future
subframes.
If, with certain TDD configurations, the number of downlink PDSCHs
which require multiple PDSCH scheduling is less than 4, in one
embodiment only the number of bits starting from the left hand side
which equal to the number of possible PDSCH subframes in the TDD
configuration are used. Since the UE knows the current TDD
configuration, it is able to determine where the meaningful bits in
the four bit bitmap field are.
For example, as shown in FIG. 14, the UE decodes a PDCCH at
subframe 1 of the TDD carrier for possible PDSCH assignments of FDD
carrier at subframes 1, 2 and 3. Since the UE knows the
uplink/downlink TDD configuration, it only reads three bits from
the left hand side of the bitmap of FIG. 15 to determine the
intended PDSCH assignment subframes.
For example if the bitmap field is [1,0,1,0], then the UE knows
that the last bit of the right hand side bears no meaning and would
interpret the current DCI containing the PDSCH assignments for
subframes 1 and 3.
In a further embodiment, instead of a fixed length of the bitmap,
the UE and the eNB may adopt the correct size bit field according
to the number of subframes required to be scheduled by
multi-subframe scheduling. This is TDD uplink/downlink
configuration dependent.
In yet a further embodiment, the redundant bits can be considered
to refer to the next available downlink subframe. In this case,
even though the downlink subframe may be scheduled in the current
subframe, it may also have been scheduled in a previous downlink
subframe. In this case, the previous configuration may be
overridden by the current configuration in some cases.
In a further embodiment, if multiple PDSCH scheduling is always
done in a consecutive fashion, two new fields may be introduced in
the existing PDSCH assignment DCI. One field may be the number of
subframe fields which represents the number of PDSCH subframes
being scheduled. This may require 2 bits. The other field is the
subframe offset which indicates the start point of the subframe
being scheduled. This field also needs 2 bits.
With regard to existing parts of the DCI content, the HARQ
information and Redundancy Version (RV) fields may be expanded into
(1, N) arrays, where N is the number of subframes being scheduled
in the DCI. Other fields, such as, radio bearer assignment,
modulation and coding scheme (MCS), among others, may remain the
same as in the current specification. All scheduled subframes can
use the same resource block (RB) and modulation scheme.
In a further embodiment, the resource allocation for multiple
subframes may be different. The DCI content may include all the
different resource allocations, and for each allocation an offset
field may be included to indicate which subframe is being allocated
with the current subframe as the reference point. For example, the
offset field could be two bits, which could indicate at most four
future subframes. In another embodiment, the resource allocation
for all the indicated subframes may be identical. In this case,
only the subframe index may need to be included.
Multiple PUSCH Scheduling
For PUSCH transmission, because of the synchronous HARQ, HARQ,
timing is harder to design, especially when the scheduling cell is
TDD which usually does not have enough downlink subframes to
cross-carrier schedule all uplink subframes in the FDD SCell. One
further design consideration is to keep the synchronous nature of
uplink HARQ.
Therefore, in accordance with one embodiment of the present
disclosure, the timing scheme for the PUSCH transmission is
illustrated with regard to FIG. 16.
As seen in FIG. 16, the PCell is a TDD configuration 1 cell and is
shown with reference 1610. The secondary cell is shown with
reference 1620 and is an FDD uplink carrier.
As seen in FIG. 16, a unified timing linkage scheme is provided.
The scheme can be applied to any TDD uplink/downlink configuration
when the scheduling cell is TDD and cross-carrier schedule uplink
subframes in an FDD cell. This is because all scheduling grants and
ACK/NACK bit transmissions are from subframes 0, 1, 5 and 6, which
are always downlink, regardless of the TDD configuration.
With the timing scheme, the synchronous nature of uplink HARQ is
maintained. The HARQ round trip time (RTT) of most subframes is 10
ms, except for subframes 3 and 8 which have a 20 ms round trip
time. This may require 10 HARQ processes on the FDD uplink. The
process ID has a one-to-one mapping with the subframe number and is
given by equation 1 below. UL HARQ Process
ID=(SFN.times.10+subframe)mod 10 (1)
Based on equation 1 above, the subframe number implicitly
represents the uplink HARQ process identifier.
With regard to scheduling, as shown by the arrows in FIG. 16, the
timing scheme uses one downlink subframe to schedule multiple
uplink subframe PUSCHs. For example, subframe 1 on the TDD cell may
schedule subframes 5, 6, 7 and 8 on the FDD SCell uplink.
Similar to multiple PDSCH scheduling described above, the multiple
PUSCH scheduling may be realized by introducing a bitmap field in
existing PUSCH grant DCI to represent the number of PUSCH grants
and the position of these uplink grants. As seen in FIG. 16, the
most number of multiple PUSCH cross-carrier scheduling required is
4. Therefore, a 4-bit bitmap field may be used to provide for all
possible scenarios. In one embodiment, a "1" may represent the
PUSCH grant presence at the subframe location and a "0" may
represent the absence of a grant at that location. In one
embodiment, the most left hand side bit may represent the `current
plus four` subframe, and the three bits next to it are for
subsequent future subframes.
Alternatively, if the multiple PUSCH scheduling is always done in a
consecutive fashion, two new fields may be introduced in the
existing PUSCH grant DCI. One is called the number of subframes
field, which represents the number of PUSCH subframes being
scheduled. In one example, this may be a 2 bit field because of the
maximum number of multiple subframes is 4.
The other field is the subframe offset which indicates the start
point of the subframe being scheduled. In other example, this field
may use 2 bits as well. Other numbers of bits however may also be
possible.
The HARQ process ID is implicitly indicated via the subframe
number, and hence there is no need to communicate it in the PUSCH
grant. Moreover, the process in a non-adaptive uplink HARQ process
and the RV is determined through a predefined sequence, as
specified in the 3GPP TS36.321 specification.
In an alternative embodiment, the uplink subframes 3 and 8 may be
left unscheduled. In this way, the number of uplink HARQ processes
required for the FDD carrier is 8, which are the same as in the
standalone FDD carrier. Moreover, all of the HARQ round trip times
would be the same at 10 ms in this case.
Cross-Subframe Scheduling
Further, the multi-subframe scheduling can improve the ability to
cross-carrier schedule subframes on the FDD carrier from the TDD
carrier. However, these multiple subframe assignments need to be
directed to the same UE. In order to introduce more flexibility,
cross-subframe scheduling is proposed.
In particular, in this embodiment, an index which indicates the
subframe positions of downlink assignments or uplink grants is
added to the corresponding DCI payload. Similar to the above
embodiments, the maximum number of subframes to schedule is four.
In this case, a two-bit index may be used to cope with all the
possible scenarios. Table 6 below gives an example of downlink
subframe position mapping indexes inserted into existing downlink
assignment DCIs.
TABLE-US-00006 TABLE 6 DL subframe position index b.sub.1b.sub.0
subframe position 00 current DL subframe on FDD carrier 01 1.sup.st
subsequent DL subframe on FDD carrier 10 2.sup.nd subsequent DL
subframe on FDD carrier 11 3.sup.rd subsequent DL subframe on FDD
carrier
Table 7 shows uplink subframe position mapping indexes inserted
into the existing DCI 0/DCI 4.
TABLE-US-00007 TABLE 7 UL subframe position index b.sub.1b.sub.0
subframe position 00 current subframe + 4 on UL FDD carrier 01
1.sup.st subsequent UL subframe on FDD carrier 10 2.sup.nd
subsequent UL subframe on FDD carrier 11 3.sup.rd subsequent UL
subframe on FDD carrier
Tables 6 and 7 provide for cross subframe scheduling by providing
the subframe position index for both the uplink and downlink.
The HARQ operations will need to be recognized by the network and
in particular by a network element such as an eNB. A simplified
network element is shown with regard to FIG. 17.
In FIG. 17, network element 1710 includes a processor 1720 and a
communications subsystem 1730, where the processor 1720 and
communications subsystem 1730 cooperate to perform the methods
described above.
Further, the above may be implemented by any UE. One exemplary
device is described below with regard to FIG. 18.
UE 1800 is typically a two-way wireless communication device having
voice and data communication capabilities. UE 1800 generally has
the capability to communicate with other computer systems.
Depending on the exact functionality provided, the UE may be
referred to as a data messaging device, a two-way pager, a wireless
e-mail device, a cellular telephone with data messaging
capabilities, a wireless Internet appliance, a wireless device, a
mobile device, or a data communication device, as examples.
Where UE 1800 is enabled for two-way communication, it may
incorporate a communication subsystem 1811, including both a
receiver 1812 and a transmitter 1814, as well as associated
components such as one or more antenna elements 1816 and 1818,
local oscillators (LOs) 1813, and a processing module such as a
digital signal processor (DSP) 1820. As will be apparent to those
skilled in the field of communications, the particular design of
the communication subsystem 1811 will be dependent upon the
communication network in which the device is intended to operate.
The radio frequency front end of communication subsystem 1811 can
be any of the embodiments described above.
Network access requirements will also vary depending upon the type
of network 1819. In some networks network access is associated with
a subscriber or user of UE 1800. A UE may require a removable user
identity module (RUIM) or a subscriber identity module (SIM) card
in order to operate on a network. The SIM/RUIM interface 1844 is
normally similar to a card-slot into which a SIM/RUIM card can be
inserted and ejected. The SIM/RUIM card can have memory and hold
many key configurations 1851, and other information 1853 such as
identification, and subscriber related information.
When required network registration or activation procedures have
been completed, UE 1800 may send and receive communication signals
over the network 1819. As illustrated in FIG. 18, network 1819 can
consist of multiple base stations communicating with the UE.
Signals received by antenna 1816 through communication network 1819
are input to receiver 1812, which may perform such common receiver
functions as signal amplification, frequency down conversion,
filtering, channel selection and the like. A/D conversion of a
received signal allows more complex communication functions such as
demodulation and decoding to be performed in the DSP 1820. In a
similar manner, signals to be transmitted are processed, including
modulation and encoding for example, by DSP 1820 and input to
transmitter 1814 for digital to analog conversion, frequency up
conversion, filtering, amplification and transmission over the
communication network 1819 via antenna 1818. DSP 1820 not only
processes communication signals, but also provides for receiver and
transmitter control. For example, the gains applied to
communication signals in receiver 1812 and transmitter 1814 may be
adaptively controlled through automatic gain control algorithms
implemented in DSP 1820.
UE 1800 generally includes a processor 1838 which controls the
overall operation of the device. Communication functions, including
data and voice communications, are performed through communication
subsystem 1811. Processor 1838 also interacts with further device
subsystems such as the display 1822, flash memory 1824, random
access memory (RAM) 1826, auxiliary input/output (I/O) subsystems
1828, serial port 1830, one or more keyboards or keypads 1832,
speaker 1834, microphone 1836, other communication subsystem 1840
such as a short-range communications subsystem and any other device
subsystems generally designated as 1842. Serial port 1830 could
include a USB port or other port known to those in the art.
Some of the subsystems shown in FIG. 18 perform
communication-related functions, whereas other subsystems may
provide "resident" or on-device functions. Notably, some
subsystems, such as keyboard 1832 and display 1822, for example,
may be used for both communication-related functions, such as
entering a text message for transmission over a communication
network, and device-resident functions such as a calculator or task
list.
Operating system software used by the processor 1838 may be stored
in a persistent store such as flash memory 1824, which may instead
be a read-only memory (ROM) or similar storage element (not shown).
Those skilled in the art will appreciate that the operating system,
specific device applications, or parts thereof, may be temporarily
loaded into a volatile memory such as RAM 1826. Received
communication signals may also be stored in RAM 1826.
As shown, flash memory 1824 can be segregated into different areas
for both computer programs 1858 and program data storage 1850,
1852, 1854 and 1856. These different storage types indicate that
each program can allocate a portion of flash memory 1824 for their
own data storage requirements. Processor 1838, in addition to its
operating system functions, may enable execution of software
applications on the UE. A predetermined set of applications that
control basic operations, including at least data and voice
communication applications for example, will normally be installed
on UE 1800 during manufacturing. Other applications could be
installed subsequently or dynamically.
Applications and software may be stored on any computer readable
storage medium. The computer readable storage medium may be a
tangible or in transitory/non-transitory medium such as optical
(e.g., CD, DVD, etc.), magnetic (e.g., tape) or other memory known
in the art.
One software application may be a personal information manager
(PIM) application having the ability to organize and manage data
items relating to the user of the UE such as, but not limited to,
e-mail, calendar events, voice mails, appointments, and task items.
Naturally, one or more memory stores would be available on the UE
to facilitate storage of PIM data items. Such PIM application may
have the ability to send and receive data items, via the wireless
network 1819. Further applications may also be loaded onto the UE
1800 through the network 1819, an auxiliary I/O subsystem 1828,
serial port 1830, short-range communications subsystem 1840 or any
other suitable subsystem 1842, and installed by a user in the RAM
1826 or a non-volatile store (not shown) for execution by the
processor 1838. Such flexibility in application installation
increases the functionality of the device and may provide enhanced
on-device functions, communication-related functions, or both. For
example, secure communication applications may enable electronic
commerce functions and other such financial transactions to be
performed using the UE 1800.
In a data communication mode, a received signal such as a text
message or web page download will be processed by the communication
subsystem 1811 and input to the processor 1838, which may further
process the received signal for output to the display 1822, or
alternatively to an auxiliary I/O device 1828.
A user of UE 1800 may also compose data items such as email
messages for example, using the keyboard 1832, which may be a
complete alphanumeric keyboard or telephone-type keypad, among
others, in conjunction with the display 1822 and possibly an
auxiliary I/O device 1828. Such composed items may then be
transmitted over a communication network through the communication
subsystem 1811.
For voice communications, overall operation of UE 1800 is similar,
except that received signals would typically be output to a speaker
1834 and signals for transmission would be generated by a
microphone 1836. Alternative voice or audio I/O subsystems, such as
a voice message recording subsystem, may also be implemented on UE
1800. Although voice or audio signal output is generally
accomplished primarily through the speaker 1834, display 1822 may
also be used to provide an indication of the identity of a calling
party, the duration of a voice call, or other voice call related
information for example.
Serial port 1830 in FIG. 18 would normally be implemented in a
personal digital assistant (PDA)-type UE for which synchronization
with a user's desktop computer (not shown) may be desirable, but is
an optional device component. Such a port 1830 would enable a user
to set preferences through an external device or software
application and would extend the capabilities of UE 1800 by
providing for information or software downloads to UE 1800 other
than through a wireless communication network. The alternate
download path may for example be used to load an encryption key
onto the device through a direct and thus reliable and trusted
connection to thereby enable secure device communication. As will
be appreciated by those skilled in the art, serial port 1830 can
further be used to connect the UE to a computer to act as a
modem.
Other communications subsystems 1840, such as a short-range
communications subsystem, is a further optional component which may
provide for communication between UE 1800 and different systems or
devices, which need not necessarily be similar devices. For
example, the subsystem 1840 may include an infrared device and
associated circuits and components or a Bluetooth.TM. communication
module to provide for communication with similarly enabled systems
and devices. Subsystem 1840 may further include non-cellular
communications such as WiFi, WiMAX, or near field communications
(NFC).
The embodiments described herein are examples of structures,
systems or methods having elements corresponding to elements of the
techniques of this application. This written description may enable
those skilled in the art to make and use embodiments having
alternative elements that likewise correspond to the elements of
the techniques of this application. The intended scope of the
techniques of this application thus includes other structures,
systems or methods that do not differ from the techniques of this
application as described herein, and further includes other
structures, systems or methods with insubstantial differences from
the techniques of this application as described herein. Further,
various embodiments are shown with regards to the clauses
below:
AA. A method at a user equipment for hybrid automatic repeat
request (HARQ) operation, the user equipment operating on a primary
carrier having a first duplex mode and on at least one secondary
carrier having a second duplex mode, the method comprising: using
HARQ timing operation of a predetermined configuration of the first
duplex mode for the at least one secondary carrier, wherein the
predetermined configuration is used regardless of the configuration
of the first duplex mode on the primary carrier.
BB. The method of clause AA, wherein the first duplex mode is time
division duplex (TDD).
CC. The method of clause BB, wherein the predetermined
configuration is chosen based on the periodicity of the primary
carrier.
DD. The method of clause CC, wherein the predetermined
configuration is TDD configuration 2 physical downlink shared
channel (PDSCH) timing for a 5 ms periodicity and TDD configuration
5 PDSCH timing for a 10 ms periodicity.
EE. The method of clause AA, wherein the predetermined
configuration is TDD configuration 5 physical downlink shared
channel (PDSCH) timing.
FF. A user equipment for hybrid automatic repeat request (HARQ)
operation, the user equipment operating on a primary carrier having
a first duplex mode and on at least one secondary carrier having a
second duplex mode, the user equipment comprising a processor
configured to: use HARQ timing operation of a predetermined
configuration of the first duplex mode for the at least one
secondary carrier, wherein the predetermined configuration is used
regardless of the configuration of the first duplex mode on the
primary carrier.
GG. The user equipment of clause FF, wherein the first duplex mode
is time division duplex (TDD).
HH. The user equipment of clause GG, wherein the predetermined
configuration is chosen based on the periodicity of the primary
carrier.
II. The user equipment of clause HH, wherein the predetermined
configuration is TDD configuration 2 physical downlink shared
channel (PDSCH) timing for a 5 ms periodicity and TDD configuration
5 PDSCH timing for a 10 ms periodicity.
JJ. The user equipment of clause FF, wherein the predetermined
configuration is TDD configuration 5 physical downlink shared
channel (PDSCH) timing.
KK. A method at a user equipment for hybrid automatic repeat
request (HARQ) operation, the user equipment operating on a primary
carrier having a first duplex mode and on at least one secondary
carrier having a second duplex mode, the method comprising:
utilizing an available uplink subframe after a predetermined
processing delay on the primary carrier for acknowledgement of a
subframe on the secondary carrier.
LL. The method of clause KK, wherein the available uplink subframe
is a next available uplink subframe after the predetermined
processing delay.
MM. The method of clause KK., wherein the predetermined processing
delay is four subframes.
NN. The method of clause KK, wherein the available uplink subframe
is determined based on a lookup table.
OO. The method of clause NN, wherein the lookup table distributes
acknowledgements between uplink subframes on the primary
carrier.
PP. The method of clause NN, wherein the lookup table ensures each
subframe on the secondary carrier is associated with an uplink
subframe.
QQ. A user equipment for hybrid automatic repeat request (HARQ)
operation, the user equipment operating on a primary carrier having
a first duplex mode and on at least one secondary carrier having a
second duplex mode, the user equipment comprising a processor
configured to: use an available uplink subframe after a
predetermined processing delay on the primary carrier for
acknowledgement of a subframe on the secondary carrier.
RR. The user equipment of clause QQ, wherein the available uplink
subframe is a next available uplink subframe after the
predetermined processing delay.
SS. The user equipment of clause QQ, wherein the predetermined
processing delay is four subframes.
TT. The user equipment of clause QQ, wherein the available uplink
subframe is determined based on a lookup table.
UU. The user equipment of clause TT, wherein the lookup table
distributes acknowledgements between uplink subframes on the
primary carrier.
VV. The user equipment of clause TT, wherein the lookup table
ensures each subframe on the secondary carrier is associated with
an uplink subframe.
WW. A method at a user equipment for downlink cross-carrier
scheduling at least one secondary carrier having a second duplex
mode using a primary carrier having a first duplex mode, the method
comprising: receiving downlink scheduling information from a
network element, the downlink scheduling information including
scheduling for a current subframe and future subframes on the
secondary carrier; and receiving data on the secondary carrier
based on the downlink scheduling information.
XX. The method of clause WW, wherein the downlink scheduling
information is received as part of a downlink control information
assignment.
YY. The method of clause XX, wherein the downlink scheduling
information is received as a bitmap.
ZZ. The method of clause YY, wherein the bitmap is of fixed size to
schedule a current subframe and a maximum number of future
subframes.
AAA. The method of clause ZZ, wherein the maximum number of
subframes is determined based on a long term evolution time
division duplex configuration.
BBB. The method of clause AAA, wherein, if not all bits in the
bitmap are needed for scheduling, the unneeded bits are ignored by
the user equipment.
CCC. The method of clause AAA, wherein if not all bits in the
bitmap are needed for scheduling, the bitmap includes redundant
scheduling for future subframes.
DDD. The method of clause YY, wherein the bitmap is of variable
length based on a number of subframes being scheduled.
EEE. The method of clause XX, wherein the downlink scheduling
information includes a first field to indicate a number of
subframes being scheduled and a second field to indicate an offset
for a scheduling start point.
FFF. A user equipment for downlink cross-carrier scheduling at
least one secondary carrier having a second duplex mode using a
primary carrier having a first duplex mode, the user equipment
comprising a processor configured to: receive downlink scheduling
information from a network element, the downlink scheduling
information including scheduling for a current subframe and future
subframes on the secondary carrier; and receive data on the
secondary carrier based on the downlink scheduling information.
GGG. The user equipment of clause FFF, wherein the downlink
scheduling information is received as part of a downlink control
information assignment.
HHH. The user equipment of clause GGG, wherein the downlink
scheduling information is received as a bitmap.
III. The user equipment of clause HHH, wherein the bitmap is of
fixed size to schedule a current subframe and a maximum number of
future subframes.
JJJ. The user equipment of clause Ill, wherein the maximum number
of subframes is determined based on a long term evolution time
division duplex configuration.
KKK. The user equipment of clause JJJ, wherein, if not all bits in
the bitmap are needed for scheduling, the unneeded bits are ignored
by the user equipment.
LLL. The user equipment of clause JJJ, wherein if not all bits in
the bitmap are needed for scheduling, the bitmap includes redundant
scheduling for future subframes.
MMM. The user equipment of clause HHH, wherein the bitmap is of
variable length based on a number of subframes being scheduled.
NNN. The user equipment of clause Ill, wherein the downlink
scheduling information includes a first field to indicate a number
of subframes being scheduled and a second field to indicate an
offset for a scheduling start point.
NNN. A method at a user equipment for uplink cross-carrier
scheduling at least one secondary carrier having a frequency
division duplex (FDD) mode using a primary carrier having time
division duplex (TDD) mode, the method comprising: utilizing a
subset of subframes for uplink scheduling of the at least one
secondary carrier, wherein the subset of subframes are downlink
subframes in all TDD configurations; and receiving acknowledgments
on the subset of subframes, wherein the acknowledgments are
received on the same subframe number as the subframe used for
uplink scheduling.
OOO. The method of clause NNN, wherein the subframes for uplink
scheduling are used to schedule multiple uplink subframes on the
secondary carrier.
PPP. The method of clause OOO, wherein the scheduling information
is received in a bitmap in a downlink control information
grant.
QQQ. The method of clause OOO, wherein the scheduling information
is received in at least two fields in a downlink control
information grant, a first field indicating a number of subframes
to be scheduled and a second field indicating a subframe
offset.
RRR. The method of clause NNN, wherein the subset of subframes are
subframes 0, 1, 5 and 6.
SSS. A user equipment for uplink cross-carrier scheduling at least
one secondary carrier having a frequency division duplex (FDD) mode
using a primary carrier having time division duplex (TDD) mode, the
user equipment comprising a processor configured to: utilize a
subset of subframes for uplink scheduling of the at least one
secondary carrier, wherein the subset of subframes are downlink
subframes in all TDD configurations; and receive acknowledgments on
the subset of subframes, wherein the acknowledgments are received
on the same subframe number as the subframe used for uplink
scheduling.
TTT. The user equipment of clause SSS, wherein the subframes for
uplink scheduling are used to schedule multiple uplink subframes on
the secondary carrier.
UUU. The user equipment of clause TTT, wherein the scheduling
information is received in a bitmap in a downlink control
information grant.
VVV. The user equipment of clause TTT, wherein the scheduling
information is received in at least two fields in a downlink
control information grant, a first field indicating a number of
subframes to be scheduled and a second field indicating a subframe
offset.
WWW. The user equipment of clause SSS, wherein the subset of
subframes are subframes 0, 1, 5 and 6.
* * * * *